<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        div {
            width: 380px;
            height: 380px;
            background-color: green;
            border: 10px solid #000;
        }
    </style>
</head>
<body>
<div>
    盒子
</div>
</body>
</html>